THE MAGNITUDE AND RISK
FACTORS OF BRUCELLOSIS IN
URBAN AND PERI-URBAN
CATTLE IN NORTHERN AND
EASTERN UGANDA
BY DENIS RWABIITA MUGIZI (PhD STUDENT)
1
BACKGROUND
• Agriculture = backbone of developing
economies
• Livestock supports 70 % of the world’s
poor
• Livestock contribute 5.2% of Uganda’s
GDP
• Most of the livestock products in Uganda
are produced by small holder farmers.
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Problem statement
• Civil strife in Northern and Eastern Uganda
concentrated the small holder farmers in and
around towns in these areas
• Genesis of urban and peri-urban farming in
these areas
• Need for food was further enhanced by the
ensuing rural-urban migration
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Problem statement Ctd…
• Urban and peri-urban
livestock farming is the
major source of unprocessed
foodstuffs in these towns
• High disease burden
including zoonotic ones
• Brucellosis
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Bovine brucellosis
• Caused by biovars of Brucella abortus, B.
melitensis and B. suis
• Causes abortion, mastitis, placentitis, orchitis
and hygromas in cattle
• Causes relapsing fever and abortion in humans
• Its zoonotic nature and resulting infertility in
cattle impact on people’s livelihoods and
health.
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Objectives
• Determine the sero-prevalence of brucellosis in
indigenous and imported cattle in urban and periurban areas of Gulu and Soroti towns in Uganda.
• Identify the associated risk factors for transmission of
brucellosis in cattle in the study areas.
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Objectives ctd ...
• Isolation, biotyping and molecular characterization of
the Brucella infecting cattle in the study areas.
• Determine the susceptibility of Brucella isolates to
commonly used anti-microbials in Uganda.
• Disseminate research information to the various
stakeholders so as to initialize mitigation strategies
against brucellosis in cattle.
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Significance of the study
• Findings will be a starting point towards
improvement of people’s livelihoods and
public health
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Study area
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Production system & Climate
• Dry climatic (21.5-34o
C)
• Bimodal annual, rainfall
of 700-800mm
10
Study design ctd
• Collected samples
• Lab. analyses
RB plate test
i-ELISA
c-ELISA
Culture and isolation
Drug susceptibility
Molecular typing
11
Drug susceptibility testing
• Was carried out using the MIC broth micro-dilution
panel method.
• The panel consisted of commonly used antimicrobials
in Uganda e.g. Gentamycin, Streptomycin,
Tetracycline, Rifampicin, Penicillin, Ampicillin,
Trimethoprim and Ciprofloxacin.
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DNA extraction and molecular typing
• Genomic DNA was extracted from colonies
using the Norgen DNA extraction kit
• Isolates confirmed as Brucella using real time
PCR (Probert et al., 2004).
• A Multiplex PCR (Bruce-ladder) protocol was
used (Lopez Goni et al., 2008) for speciation
• Biovar and genotype identification was done
using the MLVA-16 assay (Le Fleche et al.,
2006).
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DATA ANALYSIS
• The data collected was captured in Excel &
transferred into SPSS version 17 for windows
• Univariable and multivariable analyses
(Logistic regression) were used to establish
relationship between disease out come and risk
factors
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RESULTS
• Sero-positivity was significantly (p < 0.001)
higher in Soroti than Gulu.
Number of included herds and animals and Brucella sero-prevalence
District
Gulu
Soroti
Overall
Herds sampled
116
50
166
Serum samples
500
507
1007
Herd sero-prevalence
19%
46%
27%
Animal sero-prevalence
6%
9%
7.5%
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Multivariable analyses of herd and individual animal risk factors
for Brucella seropositivity in cattle in Gulu
Variable
Category
p-value
OR
95% C.I for OR
Lower
Upper
Herd level
Herd size
0.03
1 - 5 cattle (ref)
-
1.0
-
-
6 - 10 cattle
0.998
< 0.0001
< 0.0001
< 0.0001
11 - 20 cattle
0.22
2.6
0.6
12
> 20 cattle
0.002
7.8
2
29
Individual animal level
Age
0.002
1 - 2 years (ref)
-
1.0
-
-
>2 - 5 years
0.12
0.4
0.1
1.3
>5 - 7 years
0.28
1.9
0.6
6.6
> 7 years
0.09
3.0
0.9
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Region of origin of the cow
< 0.0001
Western Uganda (ref)
-
1.0
-
-
Central Uganda
0.3
0.5
0.1
1.8
Northern Uganda
< 0.0001
0.1
0.05
0.4
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Multivariable analyses of herd and individual animal risk factors
for Brucella seropositivity in cattle in Soroti
Variable
Category
p-value
OR
95% C.I for OR
Lower
Upper
Herd level
Introduction of new cattle in last 2 years
Keeping pigs
No (ref)
-
1.0
-
-
Yes
0.01
6.8
1.6
29.5
Yes (ref)
-
1.0
-
-
No
0.02
4.9
1.2
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Isolates
• 11 isolates obtained from 207 milk
samples (5.3%)
• All the isolates were from sero-positive
cattle (11/17)
• All isolates were bio-typed and confirmed
with monospecific sera as B. abortus
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Drug susceptibility of isolates
MIC (µg/ml) for B. abortus isolates
Antimicrobial
Isolate range (µg/ml)
CLSI recommended susceptibility
break point
No. of isolates with MIC
above the CLSI values
Ampicillin
64-128
0.25-8
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Ciprofloxacin
0.5-1
0.12-1
0
Gentamicin
>16
≤4
11
Streptomycin
>256
≤8
11
Tetracycline
2-4
≤1
11
Florfenicol
16-32
---------
---------
Sulfamethoxazole
>1024
≤0.056-0.1
11
Trimethoprim
8-16
0.05
11
Chloramphenicol
>64
0.25-4
11
Cefotaxime
>2
0.5-2
11
Ceftazidime
>16
-------
---------
Penicillin
>16
0.25-8
11
Linezolid
>16
-------
---------
Rifampicin
2-4
0.06-4
0
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Bruce-ladder agarose gel picture
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Gel picture showing MLVA-16 assay; locus 1-6; extreme left,
right and intermedite lanes = ladder, lane 2 (left) = B. Suis
and 11 samples
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Biovar isolated
• Conclusion awaits sequence alignment
• But a quick blast search revealed that all
the 11 isolates bare a close relationship to
Brucella melitensis biovar abortus 2308.
This is a wild strain of the rough vaccine
strain RB51.
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Policy Guidance
• Urban and peri-urban farmers are advised
to keep smaller manageable herds of high
producing cattle
• Cattle should be bought from brucella free
herds, or screened before introduction
• Rifampicin remains the drug of choice in
treating brucellosis in humans
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THANK YOU
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